Lightweighting of PET containers is front and center in packaging change, but cracking down on weight isn’t the only focus of material innovation.

Temperature spikes during hot-fill operations can cause warping in PET containers, resulting in labeling foul-ups or worse. A new blowmolding process by Liquid Container resolves the issue. Source: Liquid Container.

Strength and light weight in a natural brown container appeals to many craft brewers, a product category targeted by the makers of Kraftpak uncoated carton board. To offset the use of virgin fiber, the manufacturer secured certifications from several responsible-forestry groups. Source: KapStone Kraft Paper Corp

Lightweights used to be the guys getting sand kicked in their eyes. Today, lightweights are the toast of the town, at least in the world of packaging materials.

Container weight represents cost when products are moving through the supply chain. Shaving a few grams from each container quickly adds up to significant savings, both in material and transportation costs. Conversions from glass to plastic characterized container economies early in the decade, and in recent years, attention has focused on thinner and lighter polymers.

Water bottles are the lightweighting leaders. From 2000 to 2007, the average weight of a 16.9-oz. bottle went from 18.9 grams to 13.8 grams. That was just the opening act, however. With environmental concerns generating greater pressure for downsized materials, efforts have redoubled. Today’s water bottles are half their previous weight, experts says, with the neck now being targeted as the last, best chance at gram reduction.

 “I wouldn’t have thought they could have gotten as far as they have in PET material reduction for water bottles,” comments Tracy Momany, vice president of the product development group at Plastic Technologies Inc., Holland, OH. True, performance expectations are lower than with other products-water isn’t filled under pressure, and spillage isn’t nearly as big an issue as with, say, grape juice-so bottle makers have more latitude in reducing rigidity. But water bottles are paving the way for viscous products and other foods to lightweight by changing people’s expectations, Momany suggests. “A lot of the weight in salad-dressing bottles, for example, is based on consumer perceptions,” she points out. “Water bottles have taught people that a container doesn’t have to be stout to deliver.”

Coatings that deliver the barrier function formerly associated with thick, rigid materials are coming into play. The folks who brought the world nylon have a new innovation: polyglycolic acid (PGA). A high-strength, polyester resin with exceptional gas-barrier properties, PGA was developed by DuPont and will enter the US market this year under the brand name Kuredux. The coating material, which can be applied to rigid or flexible plastics, will be produced by Kureha Corp., a Japanese manufacturer that has set up shop next to DuPont’s Belle, WV, plant. A recyclable bioderivative, PGA could enable lightweighting of a broad spectrum of food and beverage containers.

Lightweighting even is coming into play in PET containers for hot-fill, though it’s an incidental benefit, allows Mark Schneider, senior director of Liquid Container’s PET technology group. Thermal stability and minimal shrink are the critical issues with hot-fill, and this spring West Chicago, IL-based Liquid Container will debut a new extrusion process that substantially increases PET’s glass transition point.

Other suppliers offer containers that can tolerate 195 to 205

Packing houses can offer value-added meats without buying additional equipment using Cryovac’s new multi-layer film. It withstands oven cooking but seals on conventional vacuum equipment. Source: Air Products Inc.

Cook-in bag

Greater convenience or longer shelf life is the driver of most package innovation. In that regard, a new ovenable cooking bag from Sealed Air Corp.’s Cryovac division is unusual: it was designed to benefit packers and other food companies that process fresh meats.

Those processors are locked in a commodity business with thin profit margins. Expanding into value-added products requires more capital than most are willing or able to invest. The idea behind Oven Ease bags is to give those companies a platform for adding marinades or rubs to raw meat, sealing the product in a conventional rotary chamber machine, and then realizing a premium at the retail or foodservice level. Several years and a few failed attempts to engineer such a bag were part of the development, but Oven Ease now is commercial, reports Don Smith, Cryovac marketing director.

The multi-layer, nylon-based bag includes an inner ply that will form a good seal on a standard machine and a tough outer ply that will withstand two hours in a 400° F oven, or four hours at 375°. Total thickness is about 3 mils.

Several different extrusion techniques were tried in creating the film. A beta application in a school-lunch commissary “wasn’t tough enough,” says Smith. “When you start operating rotary chamber machines at higher temperatures, it creates a whole new set of problems.” But packers were intrigued by the possibilities, and “it was that dialogue that gave us the encouragement to continue development.”

Foodservice is the bag’s obvious starting point, he adds. Cross contamination is a major concern, and with the ovenable bag, cooked meats can be kept warm and moist inside the bag for hours without fear. Tyson Foods, Cryovac’s school-commissary partner, freezes cooked hamburgers, then ships the still-sealed bags to schools for reheating and serving. “Cooked hamburgers are going to be the future for school lunches,” Smith predicts.

Winning retail space will be a bigger challenge. People expect to remove fresh meats from their packages before putting them in an oven, and even if they knew about ovenable bags, they wouldn’t know where to look for them in a store. But for ribs and other products that usually require preparation, the bags are a convenience, and a convection oven, not a microwave, is the preferred medium for raw meats. “Retailers may be the key to connecting what the consumer wants and what the processor supplies,” observes Smith.

Work for the Department of Defense resulted in a retortable pouch that can be torn open to double as a bowl after reheating. Source: Ampac Flexibles.

Chain-reaction changes

The easy-open end was heralded as the Great Convenience Leap Forward in the can segment a decade ago. Basic bugs have been worked out-the pull-ring that breaks off is a less likely event than it was a few years ago-but the slow march forward continues, as suppliers develop new materials in response to specific types of food products.

Acidic foods are always tough on the lining of a sanitary can, and the rivet that holds an easy-open pull ring is particularly vulnerable to corrosion. Conservas La Costena SA de CV, one of Mexico’s largest canners of fruits and vegetables, experienced particular difficulty with La Costena brand pickled peppers. Besides the vinegar and brine solution, the capsaicin in the chili peppers was extremely corrosive. A simple solution would have been to switch to a gold aluminum lining, but the implied purity of a white coating was viewed as a marketing advantage.

“They’re looking for differentiation,” explains Enzo Orellana, a market development manager for Grace Davison Materials & Packaging Technologies, Cambridge, MA. The titanium dioxide pigment for white is especially prone to corrosion, necessitating three or more epoxy coats. The cost and time to create such a thick coating-the vertically integrated Ecatepec, Mexico-based manufacturer fabricates its own cans-drove La Costena to ask coatings specialists at Grace Davison to come up with a better solution two years ago.

“There is a lot of art associated with the science,” and it took a year for Grace to come up with a modified epoxy base coat and top coat to meet the challenge. A year of testing and limited-batch commercialization followed. Now, La Costena is primed for a broader rollout. Any tomato-based product or chicken broth is a candidate for the coating system, offered under the Apperta brand. Paprika oil may be the ultimate food test of corrosion resistance, adds Orellana.

Material changes are constant, and the retortable, peelable end is the next challenge to be met. The lids are composed of aluminum foil or polymeric laminate, while the pull ring is metal. Besides dealing with the different metallic properties, the lining has to act as an adhesive sealant that fuses with the lid during retort. “We’ve been working on that type of product for the last year,” says Orellana, with field testing about to begin.

Spouted pouches are a small part of the US drink market, but they are huge overseas. The Weider energy drink pouch (middle) sold 100 million units last year in Japan.

Pouches' cheery outlook

Hot-fill and retort are old-school processes in food and beverage manufacturing, more closely associated with the 19th Century than the 21st.  But as Liquid Container’s ThermaSet line illustrates, material innovation is breathing new life into these processes.

Spouted pouches are another case in point. While billions of these alternatives to glass and rigid-plastic bottles are hot-filled globally each year, “North America is basically virgin territory,” says Steve Gosling, president of Plymouth, MA-based Cheer Pack North America. He puts annual North American volume at 50 million, with only a fraction used for food products.

Cheer Pack scored its first hit in 2008 with Squish’ems, an applesauce-based fruit snack from Dole Packaged Foods Canada. More recently, it began supplying pre-made rolls of pouches for Mish Mash, a similar snack from Plum Organics. Both products are hot filled by Eco-Container Corp., a Mississauga, ON, copacker.

The oversized, resealable cap on the pouches elevates the flexible container to a higher level of convenience that mothers in particular find appealing, Gosling believes. Those women grew up with the stab pouch, and while many became fans, they recognize its messiness, especially in the hands of a preschooler. The Cheer Pack pouch overcomes the problem and provides assurance against choking.

Spouted pouches are enormously successful in Asia and Europe. McDonald’s outlets in France recently began using spouted pouches for an applesauce product; in Japan, an energy-drink manufacturer sells 100 million spouted pouches a year.

Cheer Pack’s Japanese owner, Hosokawa Yoko, invented the side-gusseted pouch, according to Gosling. Cheer co-owner, Gualapack of Italy, created the spouted pouch’s injection molded cap. If projected sales growth materializes, Gosling says CDF Corp., Cheer’s third owner and the firm where Gosling splits time as technical director of new product development, will begin manufacturing the caps later this year.

The pouches are made with an outer layer of PET, 12 microns thick, with an inner 90-micron layer of polyethylene sandwiching 7 microns of aluminum foil. A new version using polypropylene for the inner ply will enter the North American market this summer, opening the way for retort applications.

Spouted pouches were a hit at Truitt Brothers’ booth during the recent Private Label Manufacturers Association show. Truitt opened a Kentucky plant in December 2008 to increase its ability to deliver retorted food in pouches, heat-sealed trays and other modern materials. Compared to a can, “the cook time is 30% less, which is why the quality is higher,” explains Ron Davis, managing director.

Davis also is enthusiastic about a new linear tear-film technology from Cincinnati’s Ampac Flexibles. The tear line is engineered into the film’s structure. Until force is applied at a side notch, the integrity of the film remains intact, even when subjected to the heat and pressure of retorting. A double layer of film on the sides keeps food away and provides a “cool grip” area after reheating the pouch in a microwave.

The pouch was developed for military MREs; once opened, the stand-up pouch doubles as the food’s container. That helps bolster’s the pouch’s sustainability claims, points out Sal Pellingra, innovation and marketing director at Ampac.

Material providers are sensitive to the sustainability push for packaging. Ampac produced an all-polypropylene pouch that technically is 100% recyclable, but there are only two collection points in the country. “Who’s going to collect those pouches and recycle them?” asks Pellingra. If pouch graphics boasted of recyclability, “that’s greenwashing,” he scoffs.

KapStone Charleston Kraft LLC has taken pains to polish its sustainable credentials. The uncoated carton board is certified by FSC, SFI, PEFC, ATFS and other responsible-forestry organizations. The material also delivers high strength in a lightweight material, points out Louie Hancock, market development manager at the Charleston, SC, mill. But the material requires virgin and hardwood fibers, undercutting sustainability claims compared to carton board with recycled content.

Trying to overcome wood fiber’s stodgy image, KapStone is pitching unbleached Kraft paper and paperboard as a hip material for companies that want to project a natural image. The mill is making a run at craft breweries and other beverage manufacturers who might see value in the strength and light weight of uncoated paperboard.

In a material category where the last big innovation was bark, innovation is a hard sell. “With the sustainability movement, Kraftpak has some benefits,” Hancock says hopefully. What’s old often returns as something new, after all. In the world of packaging materials, though, it’s no great stretch to find truly innovative new materials.

For more information:

Sal Pellingra, Ampac Flexibles, 513-551-1274,
Steve Gosling, Cheer Pack North America, 508-591-6741,
Don Smith, Cryovac Division, Sealed Air Corp., 864-879-3861
Enzo Orellana, Grace Davison Materials & Packaging Technologies, 617-876-1400
Louie Hancock, Kapstone Charleston Kraft LLC, 843-745-3108,
Mark Schneider, Liquid Container, 630-562-5933,
Tracy Momany, Plastic Technologies Inc., 419-867-5415

Future material haunted by old shibboleths

Uneven heating is the biggest shortcoming of microwave cooking and heating, and judicious use of metal could address that issue. While some anecdotal evidence of home use of metal containers in microwaves exists, food manufacturers generally steer clear of steel and aluminum containers.

Part of the reluctance to use metal may be a residue of microwave’s early days, when microwave makers plastered stickers on their appliances, warning against putting any metal inside. Microwave cookbooks echoed the taboo. When magnetron tubes were sheathed in glass, the warning was appropriate: an errant energy wave could create a spark and shatter the glass. Ceramic covers replaced glass in the early 1970s, yet metal phobia persists. Industry groups make periodic stabs at changing perceptions and encouraging metal use, to little if any avail.

The most recent occurred two years ago, when European suppliers of steel and aluminum packaging commissioned a study by Germany’s Fraunhofer Institute for Process Engineering and Packaging on the efficacy of metal packaging in microwaves. Heating times were longer than in comparable plastic containers, researchers concluded, but more uniform heat transfer occurred. Moreover, in 1,000 experiments there wasn’t a single incidence of sparking. Some caveats exist: shallow and wide metal containers are required, lids should be removed, and a single container should be placed in the middle of oven, without touching the walls.

“I don’t know what is holding back a transition to metal,” sighs Mike Dunleavy, communications director for Crown Holdings (Crown Food Europe helped fund the Fraunhofer study). “It’s an effective tool, it’s completely recyclable, and a number of microwave containers have some metal on them, but no one has gone to a whole metal container.”

Steak and kidney pies in tinned plates are sold in Europe, and Dunleavy suspects some buyers opt for the convenience of a microwave over a convection oven when heating them at home. Though he lacks evidence, “people go for ease,” he reasons.

Myths and misunderstandings surrounding microwaves and metal are fading, Dunleavy believes, but the future of specialty containers with metal remains uncertain. “It’s up to the CPGs to take the lead with consumers,” he concludes. If that ever happens, it’s likely to be in Europe.  

‘Working to make sustainability sustainable'

Sustainability skeptics saw the Great Recession as the death knell for efforts to wring waste and reduce greenhouse gas (GHG) emissions from packaging and production. Instead, the sustainability movement is gaining momentum, with the beast of Bentonville prodding food companies to get involved.

Wal-Mart’s sustainable-packaging scorecard was unveiled at Pack Expo in Chicago in fall 2006, and since then the mass merchandiser has expanded beyond packaging, urging suppliers to critically evaluate all of their practices. At a meeting in July with 1,500 suppliers and sustainability leaders, the company announced development of a global sustainable product index. “At Wal-Mart, we’re working to make sustainability sustainable, so that it’s a priority in good times and in the tough times,” proclaimed president and CEO Mike Duke.

Suppliers are strongly encouraged to benchmark and quantify their GHG emissions, solid-waste levels and resource use and to provide transparency to their efforts to reduce them. Its customers want product lifecycle information, Duke maintained, and packaging is low-hanging fruit in delivering responsible products. It also provides attractive returns: a 5% cut in primary and secondary packaging would lower its global supply-chain costs $11 billion by 2013, the retailer estimates, with $3.4 billion of that flowing directly into Wal-Mart’s coffers.